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The Francis Crick Papers

Letter from Vladimir Vand to William Cochran and Francis Crick pdf (86,555 Bytes) transcript of pdf
Letter from Vladimir Vand to William Cochran and Francis Crick
Number of Image Pages:
1 (86,555 Bytes)
1951-12-13 (December 13, 1951)
Vand, Vladimir
Cochran, William
Crick, Francis
Original Repository: Wellcome Library for the History and Understanding of Medicine. Francis Harry Compton Crick Papers
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Reproduced with permission of Glasgow University. Archive Services.
Exhibit Category:
The Discovery of the Double Helix, 1951-1953
Box Number: 68
Folder Number: PP/CRI/H/1/5
Unique Identifier:
Document Type:
Letters (correspondence)
Physical Condition:
Series: Notes and Drafts
SubSeries: Notes and Drafts 1950-1955
Folder: "Evidence for the occurrence of the Pauling-Corey alpha-helix in synthetic polypeptides"
13th December, 1951.
Dear Dr. Cochran and Crick,
I thank you for your letter of 12th December.
I started a numerica1 calculation for the Pauling helix some time ago by preparing a few graphs of Cn functions, intending to try them on the data of Mrs. Hodgkin for insulin. However, I did not get very far beyond this stage, so that if you are going ahead with numerical calculations, it would be a pity to duplicate them here.
I think that a graphical method might be quite adequate, the evaluation being done by superimposing over the Cn graph a sheet of tracing paper with a properly oriented square net drawn on to it, the scale of the net depending on r and its orientation on the z co-ordinate of the atom. In this way the values of Cn are evaluated on points of a standard square net in reciprocal space, and contributions from different atoms are thus rapidly added at each point of the net.
The Sn values can be obtained from the Cn graphs by providing a separate angular scale, say in red. I am sending you a part of my Co graph, in case you have not already plotted one; the evaluation is, as you will see, very rapid. Do you think a graph like this should be included in the paper, or in some subsequent papers dealing with numerical results?
Yours sincerely,
V. Vand.
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